SEOUL, Jan 4 (Reuters) - Hyundai Motor and affiliate Kia Motors expect their vehicle sales to rise 1.5 percent this year, lagging industry growth forecasts, after missing their target in 2015 for the first time since the 2008 global financial crisis.

The once out-performers in the global industry have been losing momentum in recent years, with demand slowing in China and other emerging markets, while Japanese and U.S. rivals making a comeback in the United States.

The South Korean pair are expected to see China sales bounce back thanks to tax cuts on small cars this year, but demand in Russia, Brazil and other key emerging markets will remain depressed, analysts said.

Hyundai and Kia, together the world's fifth-largest automaker by sales, are also bracing for a weaker recovery in South Korea and the United States.

"Business uncertainty has grown," Chung Mong-koo, chief of the family-run Hyundai Motor Group, said in a statement.

"The world economy is expected to continue its low growth because of China's economic slowdown, low oil prices and jitters in emerging markets stemming from U.S. interest rate hikes," the 77-year-old said.

The automakers forecast their global sales would rise to 8.13 million vehicles in 2016, or 1.5 percent, compared with the 2.9 percent rise in overall global vehicle sales projected by their think-tank.

The South Korean duo posted flat 2015 sales of 8.01 million vehicles, falling short of their 8.2 million target.

Hyundai Motor expects 2016 sales to reach 5.01 million vehicles, after posting 2015 sales of 4.96 million vehicles -below its earlier target. Kia Motors set its 2016 goal at 3.12 million vehicles, after selling 3.05 million vehicles - below its earlier goal.

Kia plans to open its first Mexico factory in the first half of 2016, while Hyundai Motor is set to start production at its fourth China factory in the second half.

"It seems that Hyundai, Kia have set a conservative target for this year, as worries about emerging markets persist," Hana Daetoo Securities analyst Song Sun-jae said.

Hyundai and Kia had higher exposure to emerging markets than their major rivals, so they would be hit harder by a slump in countries such as Brazil and Russia, he added.

Shares in Hyundai Motor ended down 3.4 percent, their lowest close in more than four months. Kia shares slid 3.4 percent in morning trade.